DESCRIPTION

im_header_int(3)
reads the value of an integer header field. These are
"Xsize", "Ysize", "Bands", "Bbits", "BandFmt", "Coding", and "Type", or any
integer meta field.

im_header_double(3)
reads the value of the integer header fields. These are
"Xres", and "Yres", or any double meta field.

im_header_string(3)
reads the value of the integer header fields. These are
"Hist", and "filename" or any string meta field.

im_header_get_type(3)
returns the GType (eg. G_TYPE_INT) for a field. It returns zero if the field
does not exist. It does not set
im_error(3),
so it's useful for test for a field's existence.

im_header_get(3)
fills the GValue with a copy of the field value, if the field exists. The
value should be zeroed but otherwise uninitialised. The value should be unset
once the user has finished with it.

im_header_map(3)
maps a function over all header fields, presenting the value of each field as
a GValue. Return non-NULL from the map function to stop iteration early. It
maps over the builtin fields first, then any meta fields.